Explanation

 Let original price = x

Selling price = x + 15% of x = 1.15x = 1500

x = 1500 / 1.15 = 1275

Explanation

This is a present perfect continuous tense.
Structure: have/has been + verb-ing
We use it for actions that started in the past and are continuing.
"Since last morning" indicates a specific point in time, which matches this tense.

Explanation

We use the present continuous tense here because it describes an action happening now.
Structure: are + verb-ing
"You are looking for someone" is the correct form.

Explanation

 "Colony" is the correct collective noun for ants

While "colony" is the most common term, "army" 

Explanation

If the phone was working, I would call you.
This is a conditional sentence (Type 2).

The structure is: If + past simple, would + base verb.

Explanation

Aren’t you tired after working all day?

After prepositions like "after", we use a gerund (verb + ing)

"After working" is correct.

Explanation

 Noman does not look very interesting in the plan.

 For third person singular (he, she, it), we use "does not" for negative present simple.

Explanation

 Passive voice in past tense: was + past participle.

"Was not called" is correct.

Explanation

We use "trained in" a subject or skill.

"Trained in first aid" is correct usage.

Explanation

 After adjectives like "delighted", we often use "to + base verb".

"Delighted to see" is the correct form.